What symptom is most classical for pinworm infection?

Perianal itching is the classic symptom associated with pinworm infection, which is caused by the parasitic worm Enterobius vermicularis. This itching occurs primarily at night when the female pinworms migrate to the perianal region to lay eggs. The nocturnal activity of the worms often leads to an intense itching sensation, prompting scratching and potential secondary infections.

While some individuals may experience other gastrointestinal symptoms, such as diarrhea or abdominal discomfort, these are not as characteristic as perianal itching. Vomiting and fever are also not typical for pinworm infections, which are generally associated with localized discomfort rather than systemic symptoms. Thus, perianal itching is recognized as the most definitive symptom for identifying pinworm infections, making it critical for diagnosis and subsequent management.